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NBME 23 Answers

nbme23/Block 1/Question#42
A 68-year-old woman comes to the office ...
Retroperitoneal fibrosis🔍

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 +17  upvote downvote
submitted by sajaqua1(390),

The patient has a prior history of hysterectomy with bilateral salpingo-oophorectomy, and received external beam radiation to the pelvis. The patient now displays hydronephrosis and hydroureter, with distal ureteral narrowing bilaterally. The likeliest option is that we are seeing adhesions from previous surgery constrict the ureters, causing this.

E) Urothelial carcinoma (also called transitional cell carcinoma) is also a possibility. What makes this unlikely is the location: bilateral. The prior hysterectomy and bilateral salpingo-oophorectomy would leave scar tissue on both sides of the body, but the odds of urothelial carcinoma arising bilaterally are very slim.

A) The patient had a hysterectomy, so the odds of recurrent cervical carcinoma are also incredibly low. C) and D) Urethral condyloma and urethral transitional cell papilloma are in the wrong location to account for bilateral urethral narrowing with hydroureter.

stinkysulfaeggs  Great explanation - just one addition. The retroperitoneal fibrosis could also be a direct consequence of the external beam radiation. It's linked to both causes. Either way, it's a better fit than urothelial carcinoma (in retrospect). +10  
spow  Why would the onset be 15 years later though? +2  
drzed  I was thinking the same thing @spow. I had put urothelial carcinoma, thinking that a field defect would result in bilateral tumor. +1  

The patient had a total hysterectomy so a recurrence of cervical cancer is virtually not possible. Retroperitoneal fibrosis commonly results from radiation therapy to the pelvis, which can lead to bilateral hydronephrosis.

 +1  upvote downvote
submitted by mousie(137),

Why not urothelial carcinoma? Or how did you rule it out? I was thinking radiation would increase risk for future CA...

 +0  upvote downvote
submitted by temmy(93),

What of if the cancer is a urothelial cancer in the bladder due to radiation therapy. would it not cause similar signs

charcot_bouchard  Chance of bilateral ureteral ca is very rare. Also preincipal r/f for transitional cell ca is Smoking not radiation +  

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